Sofia is one of the best cities in Eastern Europe when it comes down to nightlife, and like Prague before it, the huge rise in tourism that the city has seen in recent years has primarily been driven by the sheer number of people who visit the city solely to sample the great value to be had on booze and fags. The price of a bottle of table wine in a restaurant is about £3 and a pint of beer costs about the same as nightclub entrance - about £1.
The main area for going out is along Vitosha Street, and many bars are open for 24 hours (its not unusual to see people staggering out of the bar and into the office after a night out). Some of the most popular include Stateside and Beer Hall Schweik in the city centre.
The best clubs are along Tsar Osvoboditel Boulevard, and that is where you will find Caramba and The Military Club.
Westernisation of the country has led to an influx of people visiting and carrying large amounts of money in a city where the principal income of many families is unemployment benefit, and consequently there is some street crime in the city so it's a good idea to carry only as much cash as you need at any one time. Lots of the bars are filled with hopeful young women looking to pick up a wealthy westerner to help them escape the poverty of their lives in Bulgaria, and many prostitutes sell themselves in tourist bars, although if you make it clear that you are not interested, they will move on.